1. Field of the Invention
The present invention relates to a pickup apparatus which converts the vibration of a string of a stringed instrument into an output electric signal.
2. Description of the Related Art
A conventional pickup apparatus as disclosed in Published Unexamined Japanese Utility Model Application No. 52-118623 has been proposed. This pickup apparatus comprises a casing and a plurality of pickup sections. Pickup signals from the individual pickup sections are supplied to respective preamplifiers provided outside the pickup apparatus for amplification. The amplified pickup signals are sent to a mixing device and an effect circuit. If the effect circuit is a distortion circuit, for example, it produces a signal with a distortion characteristic to the pickup signals. The distorted signal is added to the original pickup signal from the associated pickup section (pickup signal without any effect added thereto), and the resultant signal is sent to an amplifier for amplification. Loudspeakers are driven on the basis of the amplified signal from this amplifier to generate a musical sound having an effect added by the effect circuit.
Since the conventional pickup apparatus simply has pickups arranged in the casing, it is necessary to provide an effect circuit inside or outside the body of a musical instrument and electrically connect it to the pickups. As a result, lead lines which electrically connect the pickups to the effect circuit run around inside or outside the instrument body, complicating the wiring. In addition, the long lead lines may easily pickup external noise, reducing the tone quality.
As a solution to this shortcoming, there has been proposed a pickup apparatus having a pickup and an effect circuit incorporated in the casing of this pickup, as disclosed in Published Unexamined Japanese Utility Model Application No. 57-43498. This pickup apparatus can overcome at least the problem of external noise originating from the presence of the long lead lines to connecting the pickup to the effect circuit. If the pickup is of an electromagnetic type in the pickup apparatus, the presence of coils causes a pickup signal having noise, such as inductive hum, to be output from the pickup. Consequently, the effect circuit inevitably adds an effect to the pickup signal carrying such noise, thus deteriorating the quality of a musical tone generated on the basis of the effect-added pickup signal.
Prior art pickup apparatus includes a single-coil-sound system and a hum-backing system. The former type pickup apparatus comprises a single pickup having a coil wound around a magnet, and presents a characteristic of good extension of treble and clear timbre. The latter type pickup apparatus comprises two pickups which have series-connected coils wound on a pair of magnets, respectively. Thus, permits noise to be eliminated by the phase difference between the outputs of the coils and provides a characteristic that facilitates picking up of bass components and presents a soft tone quality.
Since the single-coil-sound type pickup apparatus and the hum-backing type pickup apparatus have different characteristics, there has been proposed a pickup apparatus which ensure the proper selection between the single-coil-sound system and hum-backing system in order to make use of these characteristics in accordance with the music to be played (see Published Examined Japanese Utility Model Application No. 57-44393).
This pickup apparatus includes a pair of pickups each having a coil wound around its associated magnet, and a changeover switch connected between these coils, the switch being provided outside the pickup apparatus, e.g., on the body of a guitar.
When the switch is turned off in the above arrangement, both coils are connected in series, so that the pickup apparatus acts as the hum-backing system. When the switch is turned on, both ends of one of the pickups are grounded, and the other pickup alone functions, whereby the pickup apparatus acts as the single-coil-sound system. The ON/OFF operation of the change-over switch during a musical performance can provides both the characteristic of the single-coil-sound type pickup apparatus and that of the hum-backing type.
According to this conventional pickup apparatus, since the changeover switch for selecting between the single-coil-sound system and the hum-backing system is provided outside the pickup apparatus, lead lines which connect the switch to the coils run around in the instrument body and thus can easily pick up external noise. deteriorating the tone quality. Further, a preamplifier for amplifying the output signals from the coils should be provided separately, so that lead lines for connecting the pickups to the preamplifier should inevitably extend around in the instrument body, further increasing noise.
As a solution to this problem, there has been proposed a pickup apparatus as disclosed in Published Examined Japanese Utility Model Application No. 63-18066, which has a pickup provided integrally with a preamplifier that processes the output signal of the pickup, thus preventing lead lines from unnecessarily running around to connect the pickup and preamplifier, thus reducing noise.
If this apparatus is so designed as to ensure switching between single-coil-sound system and the hum-backing system in accordance with a music to be played, as described above, the changeover switch needs to be provided outside the pickup apparatus. Although this apparatus can prevent the occurrence of the noise originating from the lead lines connecting the pickups and the preamplifier, it cannot prevent the generation of noise originating from the lead lines connected to the changeover switch.